JPH02264910A - Optical system driving device for optical apparatus - Google Patents

Abstract

PURPOSE:To execute focusing and zooming with accuracy by constituting integrally a motor supporting plate for driving a photographing optical system and a lens barrel, and on the other hand, constituting integrally a diaphragm device case for constituting one end plate of a diaphragm device and the lens barrel. CONSTITUTION:A motor frame for supporting a magnet rotor 1 and stator yoke members 2a - 2d and coils 4a, 4b of each motor for focusing and zooming consisting of a pulse motor, respectively in supported by a lens barrel constituting member 30, and a cover 31 of a gear mechanism is attached pivotally to a hinge 30c formed on the outside end face of the lens barrel constituting member 30. Since the lens barrel constituting member 30 becomes the motor frame, an inter-axis distance of a barrel constituting member 30 becomes the motor frame, an inter-axis distance of a motor axis and other rear axis is invariable, and accordingly, a motion transfer can be executed with high accuracy. Also, a diaphragm device case and a lens barrel are constituted integrally and it will suffice that a constituting member of a diaphragm unit is attached to the lens barrel, therefore, the optical or optical path center of the lens barrel and the optical or optical path center of the diaphragm unit always coincide with each other.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an optical system drive for performing autofocus and auto iris in a photographing optical system such as a zoom lens in an optical device such as a video camera or a still video camera. It is related to the device.

[Prior Art] Conventionally, focus adjustment and aperture adjustment of photographic optical systems used in video cameras, etc. have been performed using linear autofocus drive devices,
For example, to drive a lens for focus adjustment, a brushed motor rotates the focus ring on which the lens is mounted via a reduction gear or a belt, and the lens is extended or retracted. , a movable coil type, and an actuator with driving and braking coils were used.

However, in the conventional example described above, the part that drives the focus ring that holds the optical lens system is a brushed motor, which requires a large installation space and weight. However, it was difficult to make it smaller.

In addition, since the drive motor uses a motor with a brush, etc., there are concerns about the reliability and durability of the mechanical parts, such as electrical noise generated by the brushes, and the start-up time and stop time of the motor rotation. Since the autofocusing method uses the output signal from the image sensor, it has drawbacks such as poor response.

On the other hand, various devices such as movable coil or movable magnet types have been proposed for light intensity adjustment devices, but all of them use analog control to drive the lens and adjust the light intensity, so there are problems with responsiveness, especially When used in connection with a video printer, etc., there were drawbacks such as the inability to clearly print out instantaneous images.

Furthermore, since a similar Chi-Yu is used to drive the zoom lens, there are drawbacks such as the difficulty of stopping zooming at an arbitrary screen, in other words, the inability to perform fine movements. Ta.

Furthermore, as mentioned above, since the motors that drive the photographing optical system and the light amount adjustment system are arranged in the optical axis direction, particularly close to the image sensor sensor side, the timing and synchronization signals of the vertical and horizontal signals of the sensor are and a transmitter that generates and 2 f! that transmits the signal. Noise is likely to occur in the signal line of other types of drivers.

General noise countermeasures include increasing the distance from the noise-generating part of the motor, that is, the part where the brushes are mounted, adding a shielding material to the motor part, and installing C-R circuit components such as noise-cancelling diodes and capacitors on the board. Various countermeasures have been taken, such as implementation, but as a result, there have been drawbacks such as increased cost and increased size.

In addition, with the trend of increasing zoom ratios in recent years, if the optical design forces the lens to be longer in the optical axis direction, there are disadvantages such as noise countermeasures becoming increasingly disadvantageous, especially for image sensor sensors. Ta.

Therefore, the present applicant has provided an improved optical system drive device that does not have the above-mentioned drawbacks (Japanese Patent Application No. 63-267875).

The optical system drive device according to the prior application is configured to drive the photographing optical system and the aperture device using stepping motors, respectively, and according to this drive device, it is possible to realize a photographing device that does not have the above-mentioned drawbacks.

FIGS. 8 to 14 show a photographing device equipped with an optical system driving device proposed by the present applicant, and the schematic structure of the optical system driving device will be described below.

In FIGS. 8 and 9, 100 is an autofocus and zoom drive device that drives the front lens 42, 200 is a rear lens 44, respectively; 300 is an iris drive device for adjusting the amount of light; 101. Reference numerals 201 and 301 are pulse motors that are the drive sources of each of the drive devices 100, 200, and 300 described above.

Note that since the autofocus drive device 100 and the zoom drive device 200 have the same structure, the same parts of both devices 100 and 200 will be described below with reference to one drawing.

In FIGS. 11 to 14, 1 is an anisotropic magnet rotor made of plastic material, 28 to 2d are stator yoke members disposed opposite to each other on both sides of the rotor, and 3a
, 3b is an iron core, 4a and 4b are excitation coils that generate a magnetic field in the stator yoke and the iron core, and these members 2a
- Pulse motor 1 by 2d, 3a, 3b, 4a, 4b
01, 201, and 301 constitute magnetic circuits.

The rotor 1 of the pulse motor 101 is pivotally supported between the upper and lower base plates 15 and the cover 11 as shown in FIGS. 11 and 12, and a pinion gear 5 is press-fitted and fixed to the end of the shaft. The mesh is transmitted to gear 6 and gear 5. A friction gear 8 rotatably attached to the rotating shaft 7a of the gear 7 meshes with a gear 13 on the outer periphery of a focus ring surrounding the photographing optical system, as shown in FIG. 10, and the focus ring is rotated. This allows the optical lens to be extended or retracted in the optical axis direction (not shown). The friction gear 8 is interposed between the friction plates 14a and 14b, and is provided with a friction function by a spring 9 and a retaining ring 12 at a constant torque value.

In addition, each member constituting the magnetic circuit is connected to the motor base plate 1.
5 and the cover 11 with screws 16a, 16b, and 17.

Further, the gear train and the friction mechanism arranged above the main plate 15 are covered with a cover 10, which holds the shaft ends of the gears 6 and 7 in the thrust direction and also serves as a soundproofing member. .

FIG. 14 is an exploded perspective view of an auto iris device for adjusting light quantity, and the auto iris device is a drive device 3 of FIG.
00, and the drive device 300 is constituted by a pulse motor 301. Note that the pulse motor 301 has the same magnetic circuit configuration and operating principle as the pulse motors 101 and 2Q1 described above.

In FIG. 14, 1 is the magnet rotor of the pulse motor 301, 2a to 2d are stator yoke members of the motor 301, 3a'EL and 3b are the coil cores of the motor 301, 4a and 4b are the coils of the motor 301, and 26 and 27 is a base plate serving as a motor frame.

The rotor 1 is pivotally supported by upper and base plates 26 and 27, and a pinion gear 21 is press-fitted into the end of the shaft and meshes with a partial gear 22g provided on a part of the outer periphery of the aperture blade support ring 22. There is. The ring 22 is rotatably fitted into the base plate 23 of the diaphragm, and the plurality of holes 22a to 22a of the ring 22 are
Fitting pins 24e of a plurality of aperture blades 24a to 24d are fitted into 22d. Then, the binion gear 2
1 rotation causes the ring 22 to rotate. On the other hand, a part of the aperture device case 25 has cam grooves corresponding to the number of aperture blades 24a to 24d, and a pin that fits into the cam groove is protruded from the opposite surface of each aperture blade. The structure is such that the aperture blades can be opened and closed by relative sliding along the cam groove of the case 25. Hereinafter, like the pulse motor unit that drives the imaging optical system, it is also possible to rotate clockwise and counterclockwise, so the amount of light, that is, the aperture diameter, can be arbitrarily varied in steps through the plurality of aperture blades. .

The base plates 15, 26, 27 and covers 10, 11 in each of the above-mentioned drive devices 100, 200, 300 are formed in an arc shape that matches the shape of the outer peripheral surface of the lens barrel.

Next, referring to FIG. 13, each pulse motor 101 to 30
The operating principle of No. 1 will be explained.

When the excitation coils 4a'EL and 4b are not energized, the poles of the rotor 1 form a magnetic path via the stator yoke, so the poles of the rotor face the stator yokes 2a and 2b. At that time, stator 2
The poles of C and 2d and the rotor do not face each other, but are shifted by a pitch (90 degrees in electrical angle). Next, when a current is applied from direction A, stator yokes 2b and 2d become N poles, and stator 2a
And an S pole occurs at 2C. Therefore, the N and S poles magnetized on the outer periphery of the rotor and each stator repel or attract each other, causing the rotor 1 to rotate counterclockwise at a constant pitch.

Next, when the A-phase is de-energized and the B-phase is energized from the B direction, an N pole is generated in the stator 2d and an S pole is generated in the stator 2C. Rotate clockwise.

Next, when electricity is supplied from B of phase A and phase B, stator 2b,
Since an N pole is generated at 2c, the rotor and stator repel or attract each other as described above, and further rotate by A pitch. By changing the combination of energization to the A-phase and B-phase coils so that the rotor and stator repel each other in a single direction,
It is possible to rotate the rotor by any angle,
Moreover, it is possible to rotate by one step angle with one pulse from a control circuit to be described later. Furthermore, it is naturally possible to rotate the coil clockwise by changing the direction of the current flowing through the coil depending on the energization pattern. In practice, the focus state of the photographing light on the imaging surface of the image sensor of the video camera is detected and supplied to the control circuit.

[Problem to be solved by the invention] In the above-mentioned prior art of the present applicant, the pulse motor 101
Since the base plates 1 and 5, which are the motor frames of motors 1 and 201, are separate from the lens barrel, the motor 1
When attaching 01 and 201 to the lens barrel, the mounting positions vary, resulting in variations in the distance between the axes between the gear that drives the focus ring and the gear of the drive motor.As a result, accurate motion transmission ( In other words, there was a risk that highly accurate focusing and zooming would become impossible.

In addition, in the light amount adjustment device, since the aperture device case 25 that constitutes one end plate of the device is separate from the lens barrel, when attaching the light amount adjustment device (i.e., the aperture unit) to the lens barrel, There was a risk that the optical or optical path center of the light amount adjusting device would be shifted from the optical or optical path center of the lens barrel due to installation error.

It is therefore an object of the present invention to eliminate the above-mentioned risks and to provide an improved optical system drive.

[Means for Solving the Problems] In the present invention, the motor support plates of the focus and zoom motors are integrated with the lens barrel, and the aperture device case 25, which constitutes one end plate of the aperture device, is integrated with the lens barrel. The present invention is characterized in that it is configured integrally with the lens barrel, thereby eliminating the dangers present in the prior art described above.

[Function] As shown in FIGS. 1 and 2, in the optical system drive device according to the present invention, the rotor and stator of the focusing motor lot are supported by the lens barrel component 30, and the gear mechanism is The cover 31 is pivotally attached to the lens barrel component 30.

Further, in the drive device of the present invention, as shown in FIG. 4, the aperture device case 25 is constructed integrally with the lens barrel 32.

Therefore, in the drive device according to the present invention, there is no possibility that the distance between the motor shafts of the focus motor and the zoom motor and the driven shaft will vary from product to product, making it possible to transmit motion with high precision. There is no longer any fear that the image will not align with the center of the photographic optical system.

[Embodiment] An improved optical system driving device according to the present invention will be described below with reference to FIGS. 1 to 7. Note that in FIGS. 1 to 7, the same members as those described in the prior art are indicated by the same reference numerals, and explanations of these same members will be omitted unless necessary.

FIG. 1 is a diagram showing the structure of a focusing motor and a zooming motor in an optical system driving device according to the present invention. In the present invention, the pulse motors 101 and 201
magnet rotor 1 and stator yoke members 28 to 2
d and the motor frame for supporting the coils 4a and 4b is a lens barrel component 30, and a stator and coils are fitted into the inner end surface of the lens barrel component 30 as shown in FIG. Stator and coil support rod 30 for
a and 30b are provided in a protruding manner. The stator and coil support rods 30a and 30b are the first
As is clear from FIG. 1, these are members corresponding to screws 16a and 16b. When assembling the device of the present invention,
First, the stator yoke members 2a to 2d are fitted onto the support rods 30a and 30b, and the coils 4a and 4b are also fitted onto the support rods 30a and 30b. Next, the cover 11 is attached to the support rods 30a and 30.
After the glaze of the magnet rotor 1 is rotatably supported by the cover 11, the support rods 30a and 3
Case 1 is achieved by partially heating the tip of 0b and crushing it.
1 are caulked and fixed to the support rods 30a and 30b. Then, a cover 31 for the gear mechanism section is attached to the hinge 30c (see FIG. 3) formed on the outer end surface of the lens barrel component 30, and the cover 31 covers the gear mechanism section including the gears 5 to 8. do.

With the above structure, the screws 16a and 16b that were necessary in the device of the prior application are not required, and the work of drilling screw holes in the base plate 15 and the screws and installation work for attaching the base plate 15 to the lens barrel are also unnecessary. Therefore, manufacturing costs can be reduced. Since the lens barrel component 30 is a motor frame, the distance between the motor shaft and other gear shafts remains unchanged, and therefore highly accurate motion transmission is possible.

4 to 6 are exploded perspective views of the aperture device and its related structures in the apparatus of the present invention. The device of the present invention differs from the device of the prior art in that the aperture device case 25 and the lens barrel 32 are integrally constructed. That is, as shown in FIGS. 4 to 6, in the device of the present invention, the end plate portion 32a of the lens barrel 32 constitutes a diaphragm device case, and a cam groove is formed in the end plate portion 32a. There is. Therefore, in the device of the present invention, it is not necessary to attach the diaphragm unit to the lens barrel, and it is only necessary to attach the constituent members of the diaphragm unit to the lens barrel 32, so that the optical or optical path center of the lens barrel and the optical or optical path center of the diaphragm unit are always match.

FIG. 7 is a block diagram of a control circuit that controls the drive units 100, 200, and 300 described above. Note that the control system of the optical system drive device in the illustrated photographing device is exactly the same as the control system of the prior art.

Photographing light 41 enters an image sensor 45 (hereinafter referred to as COD) via an AF lens (front lens) 42, an auto iris 43, and a zoom lens (rear lens) 44. 53 is an oscillator that generates timing and synchronization signals for the vertical and horizontal signals of the sensor 45, and 54 is a driver that transfers these signals.The output signal from the CCD 45 is supplied to the focus detection circuit 6 and the light amount detection circuit 47, and , and is configured to be outputted via the video processing circuit 48. The focus detection circuit 46 detects the focal length state of the photographing light on the imaging surface of the CCD 45 by detecting a component in a certain frequency band of the imaging output signal, and supplies the detection signal to the focus control circuit 49. The focus circuit 49 converts the detection signal into a specified number of steps, and depending on the number of steps, the logic circuit drives the control circuit and specifies the coil of the pulse motor 101 for driving the photographing optical system. energize the number of pulses and
The F lens (ie, the front lens) 42 is extended or retracted and is controlled to be in focus. Naturally, the amount of lens movement is set to a fixed value in response to a designated pulse to the pulse motor 101.

The light amount detection circuit 47 detects the amount of photographing light incident on the CCD 45 by detecting the signal level of the imaging output signal, and supplies the detection signal to the aperture control circuit 50. Further, the diaphragm control circuit 50 converts the detection signal into a specified number of steps, and depending on the number of steps, the logic circuit drives the control circuit to apply the specified number of pulses to the coil of the pulse motor 301 that drives the light amount adjustment system. energize and obtain the appropriate amount of light (
The drive is controlled so that the condition is (caliber). Similarly to the photographing optical system described above, in response to a designated pulse to the pulse motor 301,
The opening/closing size of the aperture blades is set to a fixed value (aperture value). In other words, the adjustment of the amount of light is determined digitally by a digital signal from the control circuit.

The rear lens 44 is driven by supplying a zoom signal to the telephoto side or wide-angle end to the zoom control circuit 51 using the manual operation switch 52 for zoom operation, and by moving the lens forward or backward or retracting it using the zoom lens driving device 200. Do the following.

[Effects of the Invention] As explained above, in the present invention, each support member of the focusing drive device and the zooming drive device also serves as a lens barrel component, and the end plate or casing of the aperture device also functions as a lens barrel component. Since it is configured as a part of the lens barrel, there is no risk of variations in the distance between the motor shaft and the driven shaft in the focus drive device and the zoom drive device, and therefore, focusing and zooming can be performed with higher precision than the prior art. In addition, since the center of the aperture device always matches the center of the lens barrel, unevenness in the image output due to obliquely incident light rays is eliminated in lens groups with short focal lengths, so that the entire screen is uniformly distributed. You can get the image. Furthermore, because of the above-described structure, the device of the present invention can reduce the number of parts and assembly time compared to the prior art, thereby reducing manufacturing costs.

[Brief explanation of drawings]

FIG. 1 shows a first diagram of an improved optical system driving device according to the present invention.
2 is a vertical sectional view of the drive device shown in FIG. 1, and FIG. 3 is a schematic front view of the device shown in FIG. 1 mounted on the lens barrel of an imaging device. 4 is an exploded perspective view of the second portion of the improved optical system drive device according to the present invention; FIG. 5 is a side view of a portion of the device shown in FIG.
The figure is a front view of the device shown in FIG. 4, FIG. FIG. 8 is a front view of a photographing device using the present invention and the technology of the prior application of the present invention, FIG. 9 is a partially cutaway plan view of the photographing device shown in FIG. 8, and FIG. 8 is an enlarged partial front view of a part of FIG. 11 is a vertical sectional view of a driving device for focusing and zooming according to the prior art, and FIG. 12 is a driving device for focusing and zooming according to the prior art. FIG. 13 is a schematic diagram of the pulse motor built into the drive device according to the present invention and the drive device according to the prior art, and FIG. 14 is an exploded perspective view of the electric diaphragm device according to the prior art. be. 1... Magnet rotor 2a to 2d... Stator yoke members 3a and 3b... Iron cores 4a and 4b... Coil 15... Base plate 11 (of the motor)... Cover 23 (of the motor)... - Main plates 24a to 24d (of the iris device)...Aperture blades 25...Aperture bag making cases 26 and 27...Main plate 30 (of the motor)...List barrel constituent members 30a and 30b...Stator and Coil support rod 31
... Cover 32 ... Lens barrel 101-301.
・・Pulse motor and 4 other people

Claims (1)

[Scope of Claims] 1. An optical system drive device configured to drive a photographing optical system and an iris for adjusting light amount by pulse motors, comprising: a lens barrel member holding the photographing optical system; An optical system drive device for an optical device, characterized in that a part of the optical system drive device is integrated with the optical system drive device.